| 摘要 |
PURPOSE:To attain a stable operation of a frame memory device, by providing line memories before and after a frame memory when an input video signal is written to the frame memory and then read out with another clock pulse. CONSTITUTION:The data obtained by giving an A/D conversion to an input video signal is written alternately to line memories 4 and 5 via a switch 2 which is switches with each hour by a pulse ZW which is obtained from a horizontal synchronizing signal. The data read out of the memories 4 and 5 is switched with each hour and in an adverse direction to the switch 2 and then applied to a frame memory 7. In case H1<H2 is satisfied between the horizontal scan period H1 of the input video signal and the horizontal scan period H2 of a reference synchronizing signal, the writing is carried out for a period excluding a horizontal blanking period BLK. Meanwhile the line memory of the other side is read out. The reading that remains when the writing is over is performed in the period BLK. Thus it is possible to read all data although a pulse CKW or a reading clock pulse CKR has a change of phase. |
